Lungs volumes capacity

RESPIRATIONRESPIRATION

LUNG COMPLIANCELUNG COMPLIANCE Expansibility of lungs per unit increase in Expansibility of lungs per unit increase in

Trans pulmonary pressure, when no air Trans pulmonary pressure, when no air movement.movement.

∆ ∆vv ________________________

∆ ∆pp Compliance of both lungs = Average Compliance of both lungs = Average 200ml/cmH200ml/cmH22OO Compliance of both lungs + thorax = Half = Compliance of both lungs + thorax = Half =

110ml/cmH110ml/cmH22OO Compliance Work- against the elastic forces of Compliance Work- against the elastic forces of

lung( that are tending to collapse the lunglung( that are tending to collapse the lung (1) Lung elastic tissue – 1/3(1) Lung elastic tissue – 1/3rdrd

(2) Surface tension in alveoli – 2/3(2) Surface tension in alveoli – 2/3rdrd

High Compliance – Emphysema, old High Compliance – Emphysema, old age. age.

Decreased Compliance – Pulmonary Decreased Compliance – Pulmonary edema, fibrosis, pneumothorax, edema, fibrosis, pneumothorax, scarring of lungs in T.B.,thickening of scarring of lungs in T.B.,thickening of pleura, absence of surfactant in new pleura, absence of surfactant in new born.born.

FRC = Expiratory reserve volume + FRC = Expiratory reserve volume + Residual volumeResidual volume

So specific lung compliance = So specific lung compliance = 200/2300 = 0.087200/2300 = 0.087

Elastance = reciprocal of compliance Elastance = reciprocal of compliance

∆∆vv == ____________ ____________

∆ ∆pp

BRONCHIAL TONEBRONCHIAL TONE

Smooth muscles in bronchi– aid in Smooth muscles in bronchi– aid in respirationrespiration

Inspiration---- bronchial dilation Inspiration---- bronchial dilation Expiration------ bronchial constrictionExpiration------ bronchial constriction Irritants, cool air , exercise---- Irritants, cool air , exercise----

bronchial constrictionbronchial constriction Circadian rhythm----- greatest Circadian rhythm----- greatest

constriction early morning and constriction early morning and greatest dilation in the evening greatest dilation in the evening

Work of Breathing Work of Breathing

Inspiration - active process, so work is Inspiration - active process, so work is done.done.

Expiration – passive processExpiration – passive process Energy consumed (work done) during Energy consumed (work done) during

inspiration – 3-5% of total energy used by inspiration – 3-5% of total energy used by bodybody

During exertion - During exertion - ↑ ventilation – both ↑ ventilation – both inspiration and expiration – active, energy inspiration and expiration – active, energy utilized up to 50 times more.utilized up to 50 times more.

Three types of work of breathingThree types of work of breathing

1. Compliance work – 65% more 1. Compliance work – 65% more work done if compliance ↓as in work done if compliance ↓as in fibrosis fibrosis

2. Airway resistance – if increased 2. Airway resistance – if increased as in COPD, 28% as in COPD, 28%

3. Tissue resistance – as elastic 3. Tissue resistance – as elastic recoil ↓ as in emphysema 7% recoil ↓ as in emphysema 7% work done. Some abdomen work done. Some abdomen muscle work.muscle work.

Lung Volumes and CapacitiesLung Volumes and Capacities Four lung volume & four lung capacitiesFour lung volume & four lung capacities

VolumesVolumes1.1. Tidal volume – Volume of air Tidal volume – Volume of air

inspired/expired with each breath – inspired/expired with each breath – 500ml500ml

2.2. Inspiratory Reserve Volume – Max extra Inspiratory Reserve Volume – Max extra volume of air inspired over & above the volume of air inspired over & above the normal tidal volume = 3000mlnormal tidal volume = 3000ml

3.3. Expiratory Reserve Volume – Max extra Expiratory Reserve Volume – Max extra volume of air expired after the end of volume of air expired after the end of normal tidal expiration = 1100mlnormal tidal expiration = 1100ml

4.4. Residual Volume – Volume of air Residual Volume – Volume of air remaining in the lungs after forceful remaining in the lungs after forceful expiration = 1200ml expiration = 1200ml

CapacitiesCapacities1.1. Inspiratory Capacity – Inspiratory Capacity – Tidal volume +Inspiratory reserve Tidal volume +Inspiratory reserve

volume = 3500mlvolume = 3500ml2. Functional Residual Capacity (FRC) – 2. Functional Residual Capacity (FRC) –

Expiratory reserve volume + residual Expiratory reserve volume + residual volume = 2300mlvolume = 2300ml

3.3. Vital Capacity – Vital Capacity – Inspiratory reserve volume + expiratory Inspiratory reserve volume + expiratory

reserve volume + tidal vol = 4600ml.reserve volume + tidal vol = 4600ml.4.4. Total lung capacity – Total lung capacity – Max volume of lung to which it can be Max volume of lung to which it can be

expanded with greatest possible effort = expanded with greatest possible effort = 5800ml5800ml

Graph ObtainedGraph Obtained

MeasurementMeasurement

Volume movement of air into and out of Volume movement of air into and out of lungs can be measured by an instrument lungs can be measured by an instrument called spirometer, except FRC.called spirometer, except FRC.

FRC measured by Helium dilution methodFRC measured by Helium dilution method Spirometer of known volume is filled with air Spirometer of known volume is filled with air

mixed with Helium at a known concentration mixed with Helium at a known concentration After normal expiration, FRC is remained in After normal expiration, FRC is remained in

the lungs the lungs FRC gases mixed with Helium & dilute itFRC gases mixed with Helium & dilute it Dilution calculatedDilution calculated

CCiiHeHe

FRC FRC == __________________ __________________ -1 x Vi-spir -1 x Vi-spir CCffHeHe

CCiiHe = Initial conc. of HeliumHe = Initial conc. of Helium CfHe = Final conc. of HeliumCfHe = Final conc. of Helium VVii-spir = volume of spirometer-spir = volume of spirometer So RV can be determined as So RV can be determined as

RV = FRC-ERVRV = FRC-ERV TLC can be calculated = FRC + ICTLC can be calculated = FRC + IC

Minute Resp. VolumeMinute Resp. Volume

Total volume of new air into the lung Total volume of new air into the lung per minute = TV x Resp. rate = per minute = TV x Resp. rate = 500x12= 6000ml(6L/ min)500x12= 6000ml(6L/ min)

Composition and partial pressures of Composition and partial pressures of gases of air does not changegases of air does not change

Vital capacity –is indication of Vital capacity –is indication of strength of respiratory muscles.strength of respiratory muscles.

FEVFEVI I = Forced expiratory volume in = Forced expiratory volume in first secondfirst second

FVC : Max amount of air that can be FVC : Max amount of air that can be exhaled with greatest possible exhaled with greatest possible expiratory effort within shortest expiratory effort within shortest possible time period.(dynamic VC)possible time period.(dynamic VC)

FEV1 : Fraction of FVC that is expired FEV1 : Fraction of FVC that is expired in first second of forceful expiration. in first second of forceful expiration. (timed VC)(timed VC)

Ratio FEVRatio FEVII / FVC = Important in / FVC = Important in determining obstructive and determining obstructive and restrictive pulmonary diseases.restrictive pulmonary diseases.

During FVC procedure – 80% is During FVC procedure – 80% is expired during first second.expired during first second.

Obstructive Diseases - FEVObstructive Diseases - FEVI I is is reduced & FVC reduced in normal reduced & FVC reduced in normal limits.( COPD, asthma, emphysema)limits.( COPD, asthma, emphysema)

Restrictive Diseases – Both FEVRestrictive Diseases – Both FEV I I && FVC reduced so ratio –same. FVC reduced so ratio –same. Pneumonia, fibrosis, kyphosis, Pneumonia, fibrosis, kyphosis, scoliosis. scoliosis.

All volume and capacities 20 All volume and capacities 20 – 25 % less in women and – 25 % less in women and greater in males, large and greater in males, large and athletic people.athletic people.

More in standing and sitting More in standing and sitting position rather in lying.position rather in lying.

Alveolar ventilation: Total vol Alveolar ventilation: Total vol of new air that is moved to of new air that is moved to gas exchange areas of lungs, gas exchange areas of lungs, 4200 ml/mint. 4200 ml/mint.

Matching of air and Blood flowMatching of air and Blood flow

Blood flow alteration depends upon:Blood flow alteration depends upon:1- The properties of capillaries.1- The properties of capillaries.

2- Local concentration of oxygen and CO2- Local concentration of oxygen and CO22

Pulmonary capillaries – collapsible.Pulmonary capillaries – collapsible. Blood flow Blood flow ↑ or ↓ according to the ↑ or ↓ according to the

ventilation of the part of the lung.ventilation of the part of the lung. If B.P. in certain capillaries ↓ beyond If B.P. in certain capillaries ↓ beyond

certain level – capillaries close off – certain level – capillaries close off – diverting blood to more ventilation area.diverting blood to more ventilation area.

Person at rest and during exercise. Person at rest and during exercise.

DEAD SPACEDEAD SPACE

The part of the respiratory tract The part of the respiratory tract which does not participate in which does not participate in exchanging the gases.exchanging the gases.

150 ml – Anatomical dead space.150 ml – Anatomical dead space.350 ml out of 500 ml gas to 350 ml out of 500 ml gas to

alveoli or other exchanging alveoli or other exchanging areas.areas.

Rate Of Rate Of BreathingBreathing

Tidal Tidal Volume Volume (ml)(ml)

Dead Dead Space Space (ml)(ml)

Ventilation (ml/min)Ventilation (ml/min)Total Pulm Dead Space AlveolarTotal Pulm Dead Space Alveolar

Ventilation VentilationVentilation Ventilation

12 500500 150150 6,0006,000 1,8001,800 4,2004,200

15 400400 150150 6,0006,000 2,2502,250 3,7503,750

2020 300300 150150 6,0006,000 3,0003,000 3,0003,000

3030 200200 150150 6,0006,000 4,5004,500 1,5001,500

4040 150150 150150 6,0006,000 6,0006,000 00

Va= Freq (Vt – Vd) Va= Freq (Vt – Vd)

Physiological Dead SpacePhysiological Dead Space In addition to anatomical dead space. In addition to anatomical dead space. Included those alveoli which are not Included those alveoli which are not

functional.functional. The air going to physiological dead space The air going to physiological dead space

called wasted ventilationcalled wasted ventilation Physiological dead space bigger Physiological dead space bigger than anat. than anat.

Dead space Dead space Advantage & disadvantage of dead space Advantage & disadvantage of dead space

Measurement of anatomical dead space by Measurement of anatomical dead space by nitrogen washout methodnitrogen washout method

Breathing in pure oxygen and breathing Breathing in pure oxygen and breathing out in Nout in N22 meter meter

VVDD = Gray area x V = Gray area x VE E (Expired Vol. of (Expired Vol. of gas) / gas) /

Pink area + Gray areaPink area + Gray area Areas measured in cm, so Areas measured in cm, so

30/30+70 x 500 = 150ml 30/30+70 x 500 = 150ml

Non Respiratory movement Non Respiratory movement of air into Resp. Tractof air into Resp. Tract

CoughCough Protective reflexProtective reflex Bronchi & trachea – very sensitive to foreign Bronchi & trachea – very sensitive to foreign

mattermatter Irritant receptors – responsive to Irritant receptors – responsive to

mechanical, chemical irritantsmechanical, chemical irritants Afferent impulses – vagus to cough center in Afferent impulses – vagus to cough center in

medullamedulla 2.5 L inspired & glottis closed, vocal cords 2.5 L inspired & glottis closed, vocal cords

shut tightly shut tightly Abdominal muscle & other expiratory Abdominal muscle & other expiratory

muscles contractmuscles contract Alveolar pressure Alveolar pressure ↑ to + 100mmHg↑ to + 100mmHg Air exploded out and posterior nares closed Air exploded out and posterior nares closed Velocity – 70 – 100 miles/hours Velocity – 70 – 100 miles/hours

SneezingSneezing

Like cough reflexLike cough reflex Irritation in nose, mechanical or Irritation in nose, mechanical or

chemicalchemical Afferent impulses through trigeminal Afferent impulses through trigeminal

nerve to sneezing center in medulla nerve to sneezing center in medulla Uvula is depressed, so expelled air Uvula is depressed, so expelled air

through nose & Monththrough nose & Month

Alveolar Surface TensionAlveolar Surface Tension

At the interface of air and water, At the interface of air and water, water molecules have great water molecules have great attraction to each other, so tend to attraction to each other, so tend to contract the surfacecontract the surface

Water lining the interior of alveoli Water lining the interior of alveoli tend to expel the air outtend to expel the air out

So alveoli tend to collapseSo alveoli tend to collapse The net effect is to cause the elastic The net effect is to cause the elastic

contractile force of entire lungs, contractile force of entire lungs, surface tension elastic forces surface tension elastic forces

SurfactantSurfactant Surface active agent, reduces the surface Surface active agent, reduces the surface

tension so preventing the full collapse of tension so preventing the full collapse of alveolialveoli

Secreted by type II alveolar cellsSecreted by type II alveolar cells Lipoprotein mixture in thin fluid layer on Lipoprotein mixture in thin fluid layer on

the interior of alveoli the interior of alveoli Composed of surfactant apoproteins, Composed of surfactant apoproteins,

phospholipids, dipalmityol-phospholipids, dipalmityol-phasphatidylcholine, calcium ionsphasphatidylcholine, calcium ions

Dipalmitoyl component reduces the Dipalmitoyl component reduces the surface tensionsurface tension

Surface tension inversely proportional to Surface tension inversely proportional to concentration of surfactantconcentration of surfactant

During inspiration water During inspiration water molecules move apart & molecules move apart & expiration close to each otherexpiration close to each other

without surfactant, alveolar without surfactant, alveolar surface tension is 50 dynes/cm2 surface tension is 50 dynes/cm2

With surfactant, alveolar surface With surfactant, alveolar surface tension is 5- 30 dynes/cm2tension is 5- 30 dynes/cm2

Law of LaPlaceLaw of LaPlace In water bubble – surface tension In water bubble – surface tension

directed inward to the centerdirected inward to the center The positive pressure in alveoli to The positive pressure in alveoli to

push the air out is expressed by law push the air out is expressed by law of Laplace of Laplace

Two factors,Two factors, Surface tensionSurface tension Radius of viscous Radius of viscous P = 2 T/R T = Surface tension, P = 2 T/R T = Surface tension,

R = Radius of viscousR = Radius of viscous

Role of surfactantRole of surfactant

Dec. STDec. ST Dec. collapse pressureDec. collapse pressure Dec. work of breathingDec. work of breathing Inc. complianceInc. compliance Prevents development of pulmonary Prevents development of pulmonary

edemaedema

Deficiency Deficiency → Respiratory distress → Respiratory distress syndrome (RDS) of newbornsyndrome (RDS) of newborn

Surfactant secretion at 6Surfactant secretion at 6thth-7-7th MONTHth MONTH of of intrauterine life into amniotic fluidintrauterine life into amniotic fluid

Surfactant secretion stimulated by Surfactant secretion stimulated by gluco-corticoid, thyroxin, epinephrine gluco-corticoid, thyroxin, epinephrine and by contact of air with alveoliand by contact of air with alveoli

Deficiency in premature babies, Deficiency in premature babies, babies of thyroid deficient, diabetic & babies of thyroid deficient, diabetic & smoker mothers smoker mothers

Smoker Smoker –– Deficient in surfactant Deficient in surfactant Premature babies also have smaller Premature babies also have smaller

alveoli so their collapse tendency is alveoli so their collapse tendency is more. more.

HiccupHiccup

Characterized by short inspiration Characterized by short inspiration because of brief contraction of because of brief contraction of diaphragm diaphragm

Glottis closed – characteristic Glottis closed – characteristic sensation and sound sensation and sound

Because of stimulation of nerve Because of stimulation of nerve ending in GIT and abdominal cavity ending in GIT and abdominal cavity

YawningYawning

Caused by the under ventilation of Caused by the under ventilation of alveoli alveoli →↓ PO→↓ PO22

Induces deep inspiration Induces deep inspiration Characterized by wide – opened Characterized by wide – opened

mouthmouth Prevent collapse of alveoli by Prevent collapse of alveoli by

increasing ventilationincreasing ventilation Also ↑ venous return Also ↑ venous return